An ancestor ‘modern in many ways’

Scientists create virtual skull from 263 real ones. Dyani Lewis reports.

A hypothetical virtual skull of the last common ancestor to all modern humans.

Aurélien Mounier / CNRS-MNHN

The first anatomically modern human – a member of our own species, Homo sapiens, that gave rise to modern populations – walked the earth around 300,000 years ago. But what did that person look like?

A virtual skull, created by Aurélien Mounier from the French National Museum of Natural History in Paris and Marta Mirazón Lahr from Cambridge University, UK, gives us clues.

Their work, described in a paper in the journal Nature Communications, also sheds light on where our ancestor’s own ancestors hailed from.

To create the skull, Mounier and Mirazón Lahr used morphological measurements taken from 263 human skulls.

Of these, 245 were nineteenth or twentieth century specimens from 21 modern-day populations – from the San and Mbuti in Africa, to Indigenous Australians, South East Asians and the Inuit of Alaska.

The remaining 18 skulls were fossils from populations of early humans, including representatives of the African Homo habilis, Neanderthals in Europe and ancient Near Eastern Homo sapiens from the late Pleistocene.

With its rounded skull, high forehead and flat face, “the ancestor is modern in many ways,” says Mounier, with hints of more archaic traits, such as more prominent brow ridges.

“It's within the variation of Homo sapiens from the Near East that are about 200,000 years old and it's right at the fringe of the variation of the whole modern humans now,” he says.

Comparing the virtual skull to five skulls from the middle Pleistocene, between 130,000 and 350,000 years ago, Mounier and Mirazón Lahr predicted that our earliest modern human ancestor was likely the result of a meeting between populations from south and east Africa.

Populations in the north of Africa, such as the relatives of the earliest known Homo sapiens fossil – a 315,000-year-old skull from Jebel Irhoud in Morocco – are unlikely to be ancestors to this predicted early human.

But, says Mounier, when it comes to picking apart the complexities of the human origin story, there is space for interpretation, “because the evidence is a bit too scarce".

More fossils could provide a clearer picture of how much variation in skull shape and size existed in past human populations.

But modelling of virtual skulls, taking into account what is known from gene flows between populations, can also pave a way forward, says Mounier.

Tree showing the human populations used to build the models. Grey crania are drawn from the samples used to compute the H. sapiens virtual ancestor (red).

Aurélien Mounier / CNRS-MNHN

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